1. Field of the Invention
The present invention relates to a tool cutting method using a tool cutting unit for cutting a workpiece having a substrate, a plurality of LED chips mounted on the substrate, and a sealing member including a fluorescent material for covering the LED chips, thereby reducing the thickness of the sealing member to a predetermined thickness providing a desired brightness of light emitted from the LED chips.
2. Description of the Related Art
In recent years, the development of a light emitting apparatus using a light emitting diode (LED) has been advanced and the LED is used for various applications in place of an incandescent lamp and a fluorescent lamp which are conventional light sources. For example, in a road traffic signal or the like, incandescent lamps covered with red, yellow, and blue color lenses as conventional signal lights are being replaced by LEDs for emitting red, yellow, and blue lights. This is due to the fact that the LED is superior in brightness and visibility and can reduce power consumption. That is, as compared with the incandescent lamp and the fluorescent lamp, the LED is superior in luminous efficiency. For such a reason, the LED is expected to be used in various cases and a light emitting apparatus having a higher usage value is being developed.
The light emitted from an LED is light having a substantially single wavelength, so that it can be used as it is in the case of emitting light having a target color. However, in the case that an LED for emitting light having a target color has not yet been developed or in the case of emitting light having a combined color such as white light obtained by combining a plurality of colors of different wavelengths, the LED cannot be used as it is. In such a case, there is used a method of dispersing a luminescent material in a sealing resin for sealing the LED. To obtain a desired brightness of light emitted from the LED, the thickness of the sealing resin must be reduced to a predetermined thickness. The upper surface of s substrate is covered (sealed) with a resin (sealing member) including a fluorescent material. Accordingly, as a conventional method, the thickness of a workpiece having a plurality of LED chips mounted on the substrate and sealed with the sealing resin is measured and the sealing resin is next cut according to the design thickness of the substrate to thereby reduce the thickness of the sealing resin to the predetermined thickness.